The present invention relates to a process for preparing a conductive coating composition excellent in physical properties such as printability, adhesion to a substrate, conductivity in the form of a coating film, environmental resistance, etc.
There has heretofore been known a process for obtaining a resistance element by mechanically dispersing carbon black or a fine graphite powder in a resin or the like. However, the resulting element involves defects such as a relatively high electric resistance, non-uniform resistance values differing from portion to portion, and a very large variation of a resistance value with a temperature increase due to a low bonding strength of the carbon black or graphite component to the resin, so that it is particularly unfit for use at relatively high temperatures.
An attempt has been made to prepare a resistance element by graft-copolymerizing an adequate polymer onto the surfaces of particles of furnace black or acetylene black having a high structure to provide a network structure (see Japanese patent publication No. 44-3826). It involves, however, a problem of loss of flexibility when the resistance is reduced to several .OMEGA..cm.